1. Field of the Invention
The disclosure pertains to compositions and methods useful for controlling corrosion. In particular, the disclosure pertains to corrosion control compositions and methods of mitigating corrosion of metals in corrosive aqueous systems.
2. Description of the Related Art
Corrosion of metal surfaces in aqueous media has long been a problem for industries such as the oil and gas industry, food/beverage industry, and wash/sanitizing industry. For example, it is well known that during the production of oil and gas several other corrosive components are present such as brines, organic acids, carbon dioxide, hydrogen sulfide, and microorganisms. These aggressive constituents can cause severe corrosion as evidenced by surface pitting, embrittlement, and general loss of metal. The metallic surfaces can be composed of high alloy steels including chrome steels, ferritic alloy steels, austenitic stainless steels, precipitation-hardened stainless steels, and high nickel content steels, but most often the less expensive carbon steels are utilized in combination with corrosion inhibitors or coatings. This problem is even more troublesome in deep-sea operations where replacement of corroded equipment is difficult and costly.
Sea water is a highly corrosive media. When sea water is brought into contact with various metals, such as during transportation of the sea water in metal pipelines, corrosion of the metal can occur. The use of oxygen scavengers has been suggested as a way to successfully prevent corrosion in pipelines exposed to sea water. Despite the relative effectiveness, this solution has two main drawbacks. First, it demands the construction of a degasification unity at each pumping station, which will represent a high initial investment. Second, the solution requires large amounts of chemicals since it is necessary to completely neutralize the entire amount of oxygen dissolved in the water each time it passes through a pumping station considering that these operations are carried out at open air. Although attempts have been made to reduce or prohibit corrosion in metals exposed to sea water, it remains extremely challenging to control the corrosion of metal surfaces contacting such highly corrosive media.
In the food/beverage and wash/sanitizing industry, solutions such as sodium hypochlorite solutions are commonly used and are highly effective as bleaches and sanitizers for cleaning a variety of surfaces. However, sodium hypochlorite solutions are corrosive to many treated surfaces, in particular, metal surfaces become highly corroded.
There are several mechanisms responsible for corrosion of metals. In corrosive water systems, the overall corrosion rate is controlled by the reduction of oxygen inhibiting the cathodic reaction. However, the most robust and cost effective water treatment programs include both anodic and cathodic inhibitors to block reactions at both the anode and the cathode.
Anodic inhibitors suppress the rate of metal ions being transferred into the aqueous environment while cathodic inhibitors act through the development of a barrier film that reduces the ability of oxygen to diffuse to the metal surface.
Despite the availability of a variety of corrosion inhibitors, there still exists a need for improved compounds and methods for providing corrosion inhibition, in addition to a need to develop less expensive, high performance corrosion inhibitors, including chemistries that provide environmental benefits, health benefits (e.g., handling and manufacturing), manufacturing energy reduction, and reduction in waste generation.